The invention relates to an instrument for the mutual position-fixtation of bone parts or sections during osteosynthesis. In surgical and orthopedic operative techniques it is frequently necessary to fix bone parts, which have been separated through surgical means or through a fracture, in an exact mutual position and to join them together under pressure. For such so-called osteosynthesis it is common to retain the bone parts to be joined together by means of metal splints which are preferably screwed to the bone parts. The affixation of the splints by means of screws frequently results in further damage to the bone. Furthermore, the splints can also cause irritation and infections.
In the course of osteosynthesis of bones which are divided in a longitudinal direction, in particular, for example, in the case of the sternum which is separated in a longitudinal direction for cardiac surgery, it is known to place wire loops around the bone parts and to twist the wire ends together, so that the wire loops come to lie under tractive force around the bone parts and hold the same together. When twisting the wire ends together, the created tractive force of the wire can be determined only by feel and therefore only very inaccurately.
A tractive force whish is of a too low order of magnitude does not hold the bone parts together under sufficient pressure, which is disadvantageous for the process of osteosynthesis. However, when the wire ends are twisted together too tightly, a buckling-type fracture of the wire can occur. If this type of fracture occurs during the surgical procedure, this entails an unfavorable prolongation of the duration of the surgery. However, such buckling-type fractures also manifest themselves only after the conclusion of the surgery, which is particularly unfavorable, since the surgical wound has to be reopened in order to insert a new wire loop. Finally, the twisted wire ends can lead to tissue irritations which could disturb and prevent the healing process.